Hybrid or bimodular contact lenses, lenses having a comparatively rigid central portion and a soft skirt can be used to correct refractive error of the eye such as astigmatism. Current products such as rigid gas permeable (RGP) and soft toric lenses for correcting refractive error include a cylindrical component in addition to any spherical corrective component that must be determined for each patient and oriented with respect to the optical region of the cornea to maintain optimal vision correction. Features are incorporated into the lens to maintain centration and radial orientation of the lens of the eye during wear. Because of the need to fit and orient the cylindrical corrective component, a large number of lenses must be maintained in inventory and individually fit and selected for each patient.
Presbyopia normally develops as a person ages, and is associated with a natural progressive loss of accommodation. A presbyopic eye often loses the ability to rapidly and easily refocus on objects at varying distances. The effects of presbyopia usually become noticeable after the age of 45 years. By the age of 65 years, the crystalline lens has often lost almost all elastic properties and has only a limited ability to change shape. Presbyopes are projected to be the single largest group of potential contact lens wearers within the next few years. However, contact lens usage decreases after around age 45 when many patients begin to need multifocal correction for presbyopia. Current multifocal contact lenses for presbyopia correction are designed to extend depth of focus with minimal reduction in image quality. However, an underlying astigmatic error can limit the overall performance of multifocal optics. For example, corneal toricity can distort soft multifocal contact lenses leading to image degradation.
Thus, there is a need for contact lenses, and in particular soft contact lenses that treat presbyopia and accommodate astigmatic error.